SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '68afbb9d925685fd8cc96879f41a77236bb03bd8601260e8a68b2268c8d8dcf6' 
  AND token = 'JShh+WL+t2Th/YmUsWSWbRlRG3ehkPpf/OLscr0zmyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}